On Sat, Aug 06, 2022 at 09:32:47AM -0700, Paul E. McKenney wrote:
> On Sat, Aug 06, 2022 at 08:31:26AM +0200, Sedat Dilek wrote:
> > Hi Al and Paul,
> >
> > I pulled latest vfs-next on top of Linux v5.19 and see this in dmesg-logs:
> >
> > root# LC_ALL=C dmesg -T | egrep -B5 -A15 'Call Trace:'
> > [Sat Aug 6 06:51:15 2022] Bluetooth: SCO socket layer initialized
> > [Sat Aug 6 06:51:15 2022] rcu: INFO: rcu_preempt detected expedited
> > stalls on CPUs/tasks: { 0-... } 6 jiffies s: 101 root: 0x1/.
>
> This is because of the CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=20 in your
> .config file. This is selected in kernels built with CONFIG_ANDROID=y,
> and results in an ultra-short 20-millisecond RCU CPU stall timeout for
> expedited grace periods. Yes, the Android guys want and are getting
> milliseconds-scale response times from synchronize_rcu_expedited().
>
> The last time someone ran into this, the upshot was that CONFIG_ANDROID
> was to be removed: https://lwn.net/Articles/899743/
>
> My guess is that the CONFIG_ANDROID-removal patches are still on their way
> into mainline (they are in -next), but I added Greg KH and Christoph on CC
> just in case some other issue arose.
Not that I know of, those changes are all now in Linus's tree.
thanks,
greg k-h
